Crimped wire terminal

Abstract: A terminal is attached to a multi conductor wire by crimping of a pair of conductor grips (21,22) around the conductors. Mechanical locking of the conductor grips maintains a firm grasp of the conductors for improved low current and/or low voltage performance. Mechanical locking is obtained using grooves (30,31) within the contact areas of the conductor grips (21,22).

Description: The present invention relates to crimped wire terminals. Crimped terminals are widely used for terminating multi conductor insulated wires. The terminal comprises a flat metal blank including pairs of wing projections for gripping an electrical wire. One pair of projections grips an insulated portion of the wire and another pair of projections grips a stripped conductor portion at the end of the wire. The insulator grips stabilize the terminal and protect the electrical interconnection between the stripped conductor and the conductor grips. Nevertheless, in-use conditions experienced by a terminal (such as flexing of the wire, vibration and thermal shocks, or jostling of the terminal) cause forces to be transmitted to the conductor grips. Over time, the conductor grip may weaken and begin to move. Conductor grip weakening is especially a problem in low current and low voltage applications where continuous, firm contact between the wire strands and the conductor grips is critical. A weakened conductor grip may cause increased resistance or intermittent contact, which is most likely to occur at low current or low voltage levels. More specifically, the invention relates to a crimped-type terminal for crimping around a multi conductor wire oriented along an axis. The crimped terminal is adapted to be joined with a mating-terminal of an electrical device or a connecting wire. The crimped terminal has a terminal body comprising a metal blank having a substantially flat central blank portion. An insulator grip extends from one free end of the central blank portion substantially perpendicularly to the axis for gripping an insulated portion of the multi conductor wire. Interconnect means are formed at the other end of the central blank portion for interconnecting with the mating terminal of the electrical device. A pair of conductor grips extends from the central blank portion between the insulator grip and the interconnect means and substantially perpendicular to the axis. The conductor grips each have a top surface for contacting an uninsulated portion of the multi conductor wire after crimping. The bottom surfaces of the conductor grips abut at respective contact areas during crimping. In a terminal of this kind described in GB-A-813 160 the conductor grip is strengthened by forming one or more ribs on the bottom surface of the blank and corresponding grooves on the top surface. After crimping, the grooves engage with the conductor and the ribs on the two wings of the conductor grip are aligned with and press against one another. The present invention achieves improved conductor grip performance by providing mechanical locking of the crimped conductor grips resulting in a more rigid attachment. According to the invention, as presented in claim 1, in a terminal of the kind referred to the conductor grips include interlocking grooves in their respective contact areas for engaging one another during crimping to decrease movement of the conductor grips along said axis after crimping, the respective grooves in the respective contact areas being substantially perpendicular to the axis and the grooves on one of the conductor grips being offset with respect to respective grooves on the other one of the conductor grips prior to crimping. The invention will now be described further, by way of example with reference to the accompanying drawings, in which: Figure 1 is a plan view of a conventional crimp-type terminal. Figure 2 is a diagrammatic view showing conventional tooling used in the crimping of a terminal. Figure 3 is a cross-sectional view showing a conventional terminal after crimping. Figure 4 is a partial bottom view showing a flat blank according to the present invention. Figure 5 is a side view of the blank shown in Figure 4. Figure 6 is a cross-sectional view of a terminal according to the present invention prior to crimping. Figure 7 is a plan view of a crimped terminal according to the present invention. Figure 8 is a cross-sectional view of the terminal of Figure 7 after crimping, taken along lines 8-8 of Figure 7. Figure 9 is a partial bottom view of an alternative embodiment of the conductor grips of the present invention. Figure 10 is a side cross-sectional view of the conductor grip along lines 10-10 of Figure 9. As shown in Figure 1, a multi conductor wire 10 is joined to a terminal 11. Multi conductor wire 10 includes an insulation covering 12 containing wire strands 13. Terminal 11 includes insulator grips 14 for gripping insulation 12 and conductor grips 15 for gripping strands 13. By crimping conductor grips 15 around wire strands 13, a cavity is formed which firmly retains wire strands 13 providing electrical continuity with terminal 11. Terminal 11 further includes connection means such as a box-type connector 16 for interconnecting with the mating terminal such as a blade terminal of an electrical device or another connection wire. Insulator grip 14 and conductor grips 15 grasp multi conductor wire 10 as a result of crimping. As shown in Figure 2, multi conductor wire strands 13 are laid within terminal 11 and the two are then placed on an anvil 17 with the conductor grips located below a punch 18. During crimping, punch 18 and anvil 17 are quickly brought together. An upper curved surface within punch 18 crimps the grips of terminal 11 onto multi conductor wire strands 13. As shown in Figure 3, wire strands 13 are tightly retained within conductor grips 15 after crimping. Nevertheless, subsequent flexing of the multi conductor wire and other forces applied to conductor grips 15 can eventually result in a weakened connection and relative motion. An improved connection is obtained using a terminal body 20 shown in Figure 4 which is formed from a flat, conductive metal blank. Insulator grips 14 extend from a central blank portion 25 substantially perpendicularly to longitudinal axis A of terminal body 20. Likewise, a conductor grip 21 and a conductor grip 22 extend from central blank portion 25 substantially perpendicularly to longitudinal axis A. Figure 4 is a bottom view of terminal body 20, i.e., opposite from the side which receives the multi conductor wire. On the bottom surface of conductor grips 21 and 22, a pair of contact areas 23 and 24 come into contact after crimping. According to the present invention, a plurality of grooves 30 are provided in conductor grip 21 and a plurality of grooves 31 are provided in conductor grip 22 such that grooves 30 and 31 pass through contact areas 23 and 24 in a direction perpendicular to longitudinal axis A. The ends of insulator grips 14 and conductor grips 21 and 22 are coined to facilitate crimping as is known in the art. Figure 5 is a side view of conductor grip 22. Grooves 31 have a depth "d" approximately equal to one-third the total width of conductor grip 22. Each groove 30 and 31 consists of a channel which may be stamped or otherwise formed in the terminal body. Each groove has a bottom surface 32 and side surfaces 33 sloping up to an intermediate surface 34. Bottom surfaces 32 and intermediate surfaces 34 all have a width "w" to facilitate interlocking of the grooves as will be described below. The terminal body of Figure 4 can be formed by any known process, such as by stamping. Respective grooves 30 and 31 are colinear but offset as shown by line 35. After formation of the flat terminal body, insulator grips 14 and conductor grips 21 and 22 are bent upward for the crimping process, for example, by rolling, such that grooves 30 and 31 are on the outside surface as shown in Figure 6. Interconnect means, such as socket 40 for a slip-on terminal, are formed by any suitable method. Any other interconnect means may alternatively be employed in the present invention, such as eyelets. Figure 7 shows a completed terminal after crimping. During crimping of conductor grips 21 and 22, grooves 30 become interlocked with grooves 31, i.e., conductor grips 21 and 22 shift axially to permit the nesting of the grooves. After crimping, the nested grooves provide mechanical locking which prevents movement of the conductor grips thereby maintaining the grasping force on conductors 13. As shown in Figure 8, conductors 13 are firmly held against the conductor body. The mechanical interlocking of grooves 30 and 31 insures that the firm contact is maintained over time. Figure 9 shows an alternative embodiment wherein grooves 31' are offset from grooves 30. As shown by lines 36 and 37, the respective grooves are interleaved when the grooves are first formed in the terminal body. Once again, the grooves are comprised of channels that may be stamped or otherwise formed in the terminal body. In this embodiment, grooves 31' do not extend all the way to the coined ends of conductor grips 21 and 22, thereby reducing wear on the surfaces of the crimping tools (i.e., punch) that would otherwise be caused by the groove edges at the coined ends.

Claims: A crimp-type terminal (11) for crimping around a multi conductor wire (10) oriented along an axis and for joining with a mating terminal of an electrical device, said terminal having a terminal body (20) comprising: a flat blank having a central blank portion (25); an insulator grip (14) extending from one end of said central blank portion (25) substantially perpendicularly to said axis for gripping an insulated portion of said multi conductor wire; interconect means (40) formed at the other end of said central blank portion for interconnecting with said mating terminal; and a pair of conductor grips (21, 22) extending from said central blank portion (25) between said insulator grip (14) and said interconnect means and substantially perpendicularly to said axis, said conductor grips each having a top surface for contacting an uninsulated portion of said multi conductor wire after crimping, said conductor grips each having a bottom surface coming into abutment with the other bottom surface at respective contact areas (23, 24) during crimping, characterised in that said conductor grips (21, 22) include interlocking grooves (30,31) in said contact areas (23, 24) thereof for engaging one another during crimping to reduce movement of said conductor grips along said axis after crimping, said interlocking grooves (30,31) being substantially perpendicular to said axis and respective grooves (30,31) on one of said conductor grips being offset with respect to respective grooves on the other one of said conductor grips prior to crimping. A terminal as claimed in claim 1 wherein said grooves (30,31) are comprised of channels formed in said conductor grips (21, 22). An electrical interconnection system comprising an insulated multi conductor wire (10) having an axis and having insulation removed from its end and a crimp-type terminal (11) as claimed in claim 1 or claim 2 crimped to grip said multi conductor wire with its insulator grip (14) gripping the insulation (12) and its conductor grips (21, 22) crimped to engage the uninsulated portion of said wire with their top surfaces and having their respective bottom surfaces in contact with one another and their respective grooves (30,31) interlocked.

Inventors: VILLENEUVE GARY LYNN, VILLENEUVE, GARY LYNN
Applicants: FORD FRANCE, FORD MOTOR CO, FORD WERKE AG, FORD FRANCE S. A., FORD MOTOR COMPANY LIMITED, FORD-WERKE AKTIENGESELLSCHAFT
Application year: 1994
Main classification: H01R4
IPC codes: H01R4